Martello Towers

Round towers about forty feet in height, of great strength, and
situated on a beach or river; so called from the Italian towers built
as a protection against pirates. As the warning was given by striking a
bell with a martello, or hammer, the towers were called Torri da Martello.

Some say that these towers were so called from a tower at the
entrance of St. Fiorenzo, in Corsica. Similar towers were common all
along the Mediterranean coast as a defence against pirates. They were
erected in the low parts of Sussex and Kent in consequence of the
powerful defence made (February 8th, 1794) by Le Tellier at the tower
of Mortella, with only thirty-eight men, against a simultaneous sea
and land attack- the former led by Lord Hood, and the latter by
Major-General Dundas.